This invention relates to continuous strip manufacturing apparatus such as continuous casting and rolling rod manufacturing apparatus, and more particularly to a control system for maintaining a desired relation between the speed of one roll stand and the speed of a preceding work means as well as maintaining a desired configuration in a loop of elongate material passing between the one roll stand and the preceding work means.
In a continuous casting and rolling apparatus, the strip or bar of metal formed in a casting wheel work means passes continuously through a plurality of roll stands or like work means driven by variable-speed motors at coordinated speeds selected to maintain a constant mass flow rate of metal strip through the roll stands. As the mass flow rate of metal strip through a roll stand is affected by various factors in addition to the roll speed of the roll stand, it is a common practice to employ a looper to sense the configuration of the loop of metal strip between the first roll stand and the casting wheel for providing a supplementary adjustment in the speed of the first roll stand. Another looper is similarly employed to sense the configuration of the loop of metal strip between the second roll stand and the first roll stand for providing a supplementary adjustment in the speed of the second roll stand. In the past, the speed of each of the first and second roll stands was controlled by supplying the speed regulator of the respective drive motor with a speed control signal simply comprising the sum of an operator selected arbitrary signal voltage proportional to the desired speed of the respective roll stand, a signal voltage proportional to the actual rotational speed of the preceding work means, and a looper signal voltage proportional to the deviation from a desired configuration of the loop of metal strip between the respective roll stand and the preceding work means. Because the operator selected arbitrary signal voltage was of the same order of magnitude as that of the speed signal voltage of the preceding work means, the speed control signal supplied to the speed regulator of either of the first and second roll stands did not vary linearly with changes in the speed of the preceding work means. Thus, a change in the speed of the casting wheel or of the first roll stand did not result in a directly proportional change in the speed of the respective subsequent roll stand.